A proposal for local water management in the Walla Walla Watershed was drafted into legislation with Washington State House Bill 1580. The final legislation (Second House Bill 1580) was codified in Chapter 90.92 RCW, providing the Partnership with guidelines for organization, structure, and function, as well as unique water management authorities.

Through RCW 90.92, the Partnership was given the following authorities and duties:

Assume the duties, responsibilities, and all current activities of the watershed planning unit and the initiating governments authorized in RCW 90.82.040.

Develop strategic actions for the planning area by building on the watershed plan.

Adopt and revise criteria, guidance, and processes to effectuate the purpose of this chapter.

Enter into agreements with water rights holders to not divert water that becomes available as a result of Local Water Plans, water bank activities, or other programs and projects endorsed by the Partnership and Department of Ecology.